But that says "Marked as unessential (if applicable)", havent played skyrim in a while but usually only the Jarls, Guildquestlines and Mainstory npcs were immortal and some could even lose that status once they werent relevant anymore. You still had like 60% named npcs like merchants you could just kill. In Starfield the most basic unimportant merchant in the corner of the map is immortal.